CA1053221A - Vertical counterflow heat exchanger apparatus - Google Patents

Abstract

VERTICAL COUNTERFLOW
HEAT EXCHANGER APPARATUS

Abstract A counterflow heat exchanger is described with two sets of heat exchanger passages separated by heat ex-changer plates disposed in substantial parallelism within the exchanger and supported so that the passages extend substantially vertically. The heat exchanger may be em-ployed as an air-to-air or as an air-to-water heat ex-changer and can be used to remove moisture or pollutants from hot exhaust air by condensation within the exchanger passages. When employed as an air-to-water heat exchanger, the water is sprayed onto the surfaces of the upper ends of one set of passages so that it flows down their length, while air is transmitted into inlets at the lower end of the other set of passages and caused to flow upward out of outlets at the upper end thereof. The ends of the heat exchanger plates are split into two end portions separated by a divider member and joined to different exchanger plates on opposite sides thereof to form the two sets of passages which allow the air and water to flow in opposite directions through such passages for counterflow heat exchange by direct lateral transfer through the thickness of the exchanger plate.

Description

l(~S;~2~
This application is ~or an improvement invention related to my prior filed u.S. patent application Serial No .
468,659, filed ~ay 10, 1974~ entitled "Air-to-Air Heat E~changer"
now U.S. Patent 3,905,850, and U.S. patent application Serial No. 473,512, filed May 28, 1974, entitled `'Grease Collecting Heat Exchanger Installation", now U.S. Patent 3,982,588.
The instant invention relates generally to fluid heat exchanger apparatus adapted for exchange of heat between flowing streams of fluid, and in particular to vertical counterflow heat exchangers which can be employed as air-to-air or air-to-water heat exchangers. The present heat exchanger apparatus is especially useful in cooling hot exhaust air with cold water for energy conservation and condensation of air pollutants, in cooling hot water with cold ambient air, or in cooling hot ambient air with cold water for air conditioning.
According to one aspect of the present invention there is provided a heat exchanger apparatus comprising counter-flow heat exchanger means including a first set and a second set of heat exchanger passages separated from each other by heat exchanger plates in heat exchanging relationship with said first and second passages on opposite sides thereof, both sets of said passages extending completely through the heat exchanger between inlets and outlets; support means for supporting the heat exchanger means so that said passages extend substantially , vertically between their top ends and bottom ends; gas trans-~ mission means for transmitting gas into inlets at the bottom :
'. ends of the first passages and causing said gas to flow upward through said first passages out of outlets at their top ends; and liquid transmission means for spraying liquid directly onto the surfaces of the heat exchanger plates in the second passages l adjacent the top ends thereof and causing said liquid to flow downward through said second passages along said surfaces and .', .

. ~

l(~S32Zl out of outlets at their bottom ends so that said liquid and said gas flow in opposite directions along the surfaces on opposite si.des of the same portion of one of said heat exchanger plates for direct counterflow heat exchange laterally through the thickness of sa~d plates.
It has ~een known to spray ~ater into one set of passages in air-to-air heat exchanger, as shown in U.S. Patent 1,4Q9,520 of Bird and U~S. Patent 2,825,210 of Carr. In the former patent the heat exchanger i~ horizontal and the water ~ :
is sprayed in the outlet end of one set of air passages so that the ~ater does not flo~ down the length of the passages.
In the latter patent the heat exchanger plates are supported by ru~ber spacers ~hich separate the two different sets of passages so that there is no appreciable direct lateral transfer of heat through the thi.ckness of the separating members in the manner of :.:
the counterflo~ heat exçh.anger of the present invention.
The pre~ent air-to-water heat exchanger apparatus has the advantage. that the exit temperature of the air being cooled or of the w~tex ~eing heated can he easily controlled by adjust-ing the ~ater flo~ or air flow with a valve or damper which may be automatic~ operated by a temperature æensor. Another ~-~ advantage is that the apparatus is reversible and can also be '~ u~ed for cool~.~g hot ~ater and warming cold air without modifi-cat;ons in the heat exchanger. In addition, the high latent ~heat of steam ox moist exhaust air can be recovered by transfer to clean water flow~ng through other passages in the exchanger fox heating ~uild~.ngs ox other uses.
i According to another aspect of the present invention there is provided a heat exchanger and condenser apparatus 3Q comprising: a plurality of counterflow heat exchanger units each including a first set and a second set of passages separated from each other by heat exchanger plates in heat exchanging : -2-:

1~5;~

relationship with the first and second passages on opposite sides thereof; support means for supporting the heat exchanger units in at least two rows so that said passages extend sub-stantially vertically between their top and bottom ends; a pair of inlet conduits each extending across one of the ends of each of the heat exchanger units in a different row; an inter-mediate conduit extending between said pair of conduits across said one end of both rows of heat exchanger units; a discharge conduit extending across the other ends of both rows of heat exchanger units; first transmission means for transmitting hot exhaust air in through said pair of conduits, through said first set of passages in said heat exchanger units and out through said discharge conduit; and second transmission means for transmitting another fluid through said second passages in said heat exchanger units in the opposite direction to said exhaust air and out through said intermediate conduit, said other fluid being colder than the exhaust air to cool said exhaust air :
sufficiently to cause gaseous pollutants therein to condense on the surfaces of said first passages as liquid pollutants which

2~ flow down said first passages and out of the heat exchanger ~ -units.
If the condensed pollutants tend to solidify as a deposit on the surfaces of the passages, they may be removed by injecting solvents or cleaning agents into the air flowing through such passages. In addition, solid particle pollutants ~, can be removed from the air by depositing water or a more viscous liquid, such as oil, on the surface of the passages to collect impinging particles and remove them with the collecting liquid.
3Q According to a further aspect of the present invention there is provided a heat exchanger apparatus comprising: ;
counterflow heat exchanger means including a first set and a `.~ t `,J 5 L . . .

l(lS;~

second set of heat exchanger passages separated from each other by heat exchanger plates in heat exchanging relationship with said first and second passages, both of said sets of passages extending completely through said heat exchanger between inlets and outlets, said heat e~changer plates having their ends split into two end portions which.are joined to different heat exchanger plates on opposite sides thereof to form said first and second passages; support means for support-ing the heat exchanger apparatus so that said passages extend substantially ~ertically between top ends and bottom ends;
first transmission means for transmitting a gas into inlets at the bottom ends of the first passages and causing said gas to flow-upward through. said first passages out of outlets at their top ends; and second transmission means for transmitting another fluid into inlets at the top ends of the second passages and cause said other fluid to flow downward through said second passages along said $urfaces and out of outlets at their bottom ends.
The splitting of the ends of the heat exchanger plates ; ~Q provides a more ef~icient heat exchanger which is capable of handling an extremely large amount of air flow in the range of hundreds of thousands of cu~ic feet per minute.
Counter~low heat exchangers have been proposed, such as in my earlier U.S. Patent 3,381,747, comprising a series of - heat exchanger plates disposed within a housing defining a multiplicity of channels or passages extending side-by-side along the housing and constructed so that fluid flowing in alternate ones of the ch.~nnels exchanges heat with the 1uid flowing in : the remainder of the channels. To be efficient, the exchanger - 3Q plates defining such channels should have large surface expanses exposed to the fluids passing through the exchanger. Toward these ends, I have found that thin metallic sheets of consider- :

' , l()S;~Z~l able width, and preferably corrugated to increase the turbulence of fluids passing through the exchanger, may be utilized in producing a highly satisfactory exchanger for many types of applications.
In the manufacture of such an exchanger, because of the flexible nature of the plates or sheets making up the exchanger plates, and the great number of plates which ordinarily make up a typical exchanger, there are certain problems presented in assembling the unit with the plates properly positioned in a permanent manner within the exchanger, and with the completed unit having the desired strength and rigidity. To be kept in mind also is any method utilized in making the exchanger should be one which lends itself to be performed without the need of using highly trained personnel, and in a quick and expeditious manner.
In the accompanying drawings which illustrate exemplary embodiments of the present invention:
Figure 1 is a diagrammatic elevation view illustrating an air-to-water heat exchanger apparatus made in accordance with one embodiment of the present invention, with parts of the exchanger housing broken - . : ` :

JC:srd 19484 3/1/78 ~(~S;~2~1 ~
away for clarity;
Fig. 2 is a perspective view of a portion of the assembly of heat exchange plates and associated water sprayer provided in the heat exchanger apparatus of Fig. l;
Fig. 3 is a horizontal section view taken along line 3-3 of Fig. 2;
Fig. 4 is a perspective view of an air-to-air heat exchanger apparatus in accordance with another embodiment of the invention; and Fig. S is a vertical section view taken along ~; line 5-5 of Fig. 4.
~ A preferred embodiment of the heat exchanger , apparatus of the present invention is the air-to-water heat exchanger apparatus shown in Fig. 1 and includes a counterflow type of heat exchanger 1. The heat exchanger includes a housing containing an assembly ' ~ of heat exchanger plates shown in Fig. 2 which form a first set and a second set of fluid passages separated by the exchanger plates in a manner hereafter described.
.. , Heat exchanger 1 is supported so that the passages extend substantially vertically between top and bottom ,~ I
ends. The bottom ends of one set of passages are connected to an air inlet conduit 2 which transmits , ~
air into such inlet from any source, such as a source of hot humid exhaust air having a temperature of, for -~

~, example, 180F. dry bulb and 140F. wet bulb. The top ends of such one set of passages are attached to an air outlet conduit 3 which discharges the air to the atmosphere after it is cooled in the heat exchanger 1 while flowing upward through the one set of passages ' -6-~. . . . .

c: t ~ 1 a , ~ 9 n ~ / 7 6 l~ ~

in the direction of ~rrows ~. "luch of the moi~ture in the air condenses on the surfaces of the passages and flows downward out of the heat exchanger apparatus through a drain. As a result, the dischargea air at outlet 3 is also of lower humidity and may have a temperature of 60F. dry bulb and 6~F. wet bulb.
The other set of passages in the heat exchanger have their top ends employed as water ~-inlets 5 by providing a water sprayer 6 either outside of the heat exchanger and above the water inlets or ; inside the heat exchanger within such inlets. Water is sprayed onto the surfaces of such other set of passages by sprayer 6 adjacent the top ends thereof and is caused to flow downward in the direction of arrows 7 along such surfaces provided by one side of the heat exchanger plates. When cooling hot exhaust air, cold water of, for example, about 40F. is delivered to the heat exchanger by sprayer 6 and hot water of, for example, about 140F. is discharged into a water outlet conduit 8 connected to th~ bottom ends of the other set of passages. As shown in Fig, 1, the heat exchanger 1 is supported in a vertical ~, position and may extend through a hole in the roof 9 of a building containing the source of the hot exhaust air.
The heat exchanger plate assembly 10 within the e~changer is shown in Fig. 2 and includes a plurality -$ ~ of exchanger plates 12, 14, 16, 18, and 20. The plates are arranged in the assembly in substantial parallelism.
Each of the plates has a length conforming sub~tantially to the length of the exchanger with which the assembly i~ to be incorporated. The plates further may be , .. , , . . , . , . :

;rc ~ ]~83-1~490 ~/2~/76 ~1 provided with corrugations extending transversely of the plates, whereby any fluid, liquid or gas, moving through the exchanger is given a degree of turbulence.
Each of the plates at each of its ends i5 '~
split with a cut 22 extending longitudinally of the plate. The cut parallels the longitudinal edges 26 and 28 of the plate, and normally is made about mid-way between the longitudinal edges, thus to divide the end of each plate into a pair of end portions or tongue segments, exemplified by tongue segments 12a ~-and 12b, of equal width.
The tongue segments of each exchanger plate end are shown bent in reverse directions. ~hus, tongue segment 12a, as shown in Fig. 2, is bent to curve outwardly (where it will meet with the housing of the exchanger which i3 assembled about the core ~ ~ element) and tongue ~egment 12b below segment 12a is ;i bent to curve inwardly. Considering exchanger ~plate 14, its upper tongue segment 14a is bent inwardly, whereas its lower tongue segment 14b is bent outwardly to meet tongue ~egment 12b. Where adjacent ends of tongue segments meet, they may be fixed together using a~overlying angle piece, such as angle piece 24, secured in place as by crimping.
It will be noted that whereas the upper tongue segment 12a of plate 12 is bent outwardly, and the lower one 12b is bent inwardly, at the opposite end of the exchanger plate the upper tongue segment 12c is bent lnwardly wherea~ the lower one is bent outwardly.
This same relationship holds true for the tongue ~,~' .; .
' ~

JC ~7 1~3~ 0 2/2~/76 ~1 segments at each set of ends of an exchanger plate. ~ ;
A divider member shown at 30, including a horizontal wall expanse 32 and a vertical marginal flange 34, may be inserted into cuts forming the tongue segments, at each set of ends of the exchanger plates. The divider member, when positioned as shown in Fig. 2, serves to separate end portions of channels defined on opposite sides of the various plates~ Thus, and considering channel 40 in Fig. 2, th0 divider separates this channel where such is defined between tongue se-g~emts 18a, 16a, from portions of channels 38 and 42 below the divider, defined between tongue segments 20b, 18b, and 16b, 14b respectively.
~ s shown in Fig. 2, one set of passages or channels 36, 40, and 44, at the end of the assembly pictured at the bottom of Fig, 2, open to the end of the assembly above the divider. At the opposite end of the assembly, these channels open up to the end of the assembly below the divider. ~he reverse i5 true for the other set of passages or channels 32, 42, ~ -, . . .
~ and 46, which at the end of the assembly pictured at ~., the bottom of Fig. 2, open to the end of the assembly below the dlvider, and at the opposite end of the assembly, open to the end of the assembly above the di~ider.

With the arrangement, and assuming thP
prese~ce of an encompassing casing, it should be ~ obvious that one set of channels may be utilized for : r~ : the passage of one body o fluid through the exchanger, and an alternating set for the passage of another body of fluid through the exchanger, with such bodies of ; ~
~,:
",j,~ :
~ -9-JC:p~ 19~8~~~9~9Q 2/2~/7~ ~1 .

fluid passing through multîple flow paths inter~persed with each other.
In making an exchanger with a core element of the type described, and when it is remembered that typically a far greater number of exchanger plates are utilized than actually pictured in Fig 2, it should be obvious that a problem arises with respect to positioning properly the adjacent exchanger plates where they extend in expanses between the ends of the ~ 10 plates. The plates usually are made of ~hin metal, : and if corrugated tran~versely of their lengths, have considerable flexibility in a transverse direction.
~'~ Further, they are easily twisted. Obviously, if the plates are not properly oriented in the aompleted exchanger with substantially uniform spacing existing between them where they extend throughout their length, ~, the efficlency of the exchanger i9 affected. ~-Thu~, according to this invention, the ~arious exchanger plates are arranged substantially as pictured in Fig. 2. During assembly, and to tie the various exchanger plates together, tying clips 48, which may be metal strips attachable ko the edges of the plate~, are assembled with the plates by fixedly attaching them to~the edgeY of the plates at regions ; spaced along the length of the assembly. The clips ; are attached to each of the opposite sets of adjacent edges in the plate~as~embly. The tying clip 48 specifically illustrated has slotted depressions formed in it, the slots receiving edge portions of the plates whlch may be twisted slightly after heing passed through the slots to hold the clip in place. The r`.~- ~
/ I
~L: --10--~C:pw l9~83-l~4~n 2/26~7~ ~1 l~ZZ~
exchanger plates are also fastened together at their ends through joinder of the tongue segments with angle pieces 24.
~s a next step in the manufacture of the exchanger, a set of adjacent longitudinal edges 26 or 28 in the exchanger plate assembly 10 is permanently fixed by embedding or encasing the edges in a re.sin slab 49. In preparing such a slab, reinforcing material, such as a fiberglass sheet, is laid down lQ along the interior of a section of the metal housing 50 of the heat exchanger. Poured over this sheet is a mass of uncured, hardenable synthetic plastic resin material 49, such as a liquid epoxy resin, which is a thermosetting resin that cures to form a hard mass.
The resin impregnates the reinforcing sheet, and the 1~-~, :
~i~ resin and sheet form a hardenable layer on the inner surface of the houæing section. The housing section, which may be made of sheet metal, constitutes a form ; ~ . , .
confining the resin layer during this stage of the i5e~ 20 manufacture~
The assembly of exchanger plates may then be f~tted within the housing section! with a set of edges - -` 2~ or 28 of the plates, as well as any tying strips 4 ccnnecting these edge~, then pressed downwardly to be sunk into the layer 49 of resin and reinforcing material. After a~period of time, on curing of the resin mass, a strong,~r~gid slab 49 of synthetic pla~tic results which bonds the longitudinal edges of the heat exchanger plates to the h~using 50. Such slab `30 ~-~ seals-the edges of the plates, and provides lnsulation ~`'7 ~ along one side of the exchanger, as well as forming a i .. ;: , . .

~C.},w 1~4~3~ 2J26~7h ~1 rigid structural element along one side of the plate assembly.
This operation may then be repeated ~y preparing in another housing section another layer of ; resin and reinorcing material similar to the one just described. The assembly of exchanger plates may then he inverted, and the edges in the opposing set of edges of the plates, together with tying strips, sunk into this layer of material. On hardening, another rigid slab is thus prepared encasing the edges of the opposing set, and forming a rigid unit of slab and various exchanger plates.
An article prepared as above includes the core element of assembled exchanger plates, having ~i cured slabs of reinforced resin uniting and sealing the edges in the opposed set of edges of the plates.
Encompassing the slabs of resinous material, and portions of the sides of the exchanger plate assembly, are ~i housing sections which are joined together to form the completed housing.
, ~¦ As shown in Figs. 2 and 3, the sprayer means J 6 may include a plurality of pairs of sprayer pipes 51 provided ln each of the water passages 38, 42, and 46 extending across their width adjacent the upper ends thereof. The sprayer pipes 51 spray water onto : , the surfaces of such passages adjacent their top ends throu~h spray openings 52 spaced along such pipes.
.
~- ~ The water flows down the length of such passages in the direction of arrows 7 since they are supported in a vertical position. The sprayer pipes 51 may be of about 1/4 inch inner diameter and are connected to ~ - ,.1 .
:-, ., , : ,.
, JC :}~w 19483-19490 2~2~/7~

32;~1 ~
larger header pipes 53 of one inch inner diame~e~ which in turn - are connected to a main line pipe 54 of 4 inch inner diameter. The main line pipe 54 is csnnected to a water supply 56 through a valve 58. The water supply may he connected to the output of a water cooling tower whose input is connected to the water outlet conduit 8 of the heat exchanger to reuse the water after it has been cooled. The valve 58 may be automatically or manually adjusted to vary the flow of water through the heat exchanger and thereby control:`the temperature of the air discharged from such exchanger through conduit 3.
In addition, the heat exchanger apparatus of Fig. 1 can be provided with a drain pipe 60 connected to a collecting basin 61 in the bottom of the air inlet conduit 2 to drain off any condensed water or 1 . :.
,~ pollutan~, such as carbonaceous vapors which con~ense from the exhaust air as liquids onto the ~urfaces o the heat exchanger passages through which the exhaust alr flows. Thus, some of the air pollutants may he chemical solvents which after condensing in the heat , ~ -exchanger run down the heat exchanger plates and are recovered through the drain 60. In order to clean the ; surface~of the heat exchanger plates and remove solids deposited on such plates, a source of cleaning liquid 62 is connected th~ough a valve 64 to the air outlet conduit 3 at the top end of the air passages of the heat exchanger. Thus, cleaning liquid is periadically 2 - ~ ~ injected into;the conduit 3 and flows down the ~urfaces of the air passages for cleaning. Alternatively, the cleaning liquid can be evaporated into the hat air , i , ~i , 'i~: ' .
~ "~'' , .
~i --13 ~C:p~ 194~ 490 2/26/7~ ~l .
~3;~
and transmitted into the inlet conduit 2 so th~t such cleaning liquid condenses on the surfaces of the first set of heat exchanger passages as the air flows upward in the direction of arrows 4. ~he condensed cleaning liquid flows downward along the surfaces of the first passages and removes any solids deposited on such surfaces. The condensed cleaning liquid is collected in the basin 61 and is transmitted through the drain 60 to a suitable evaporator (not shown) for reevaporating it into the hot air stream to provide a continuous cleaning operation.
Figs. 4 and 5 show another embodiment of the vertical counterflow heat exchanger apparatus of the present invention including a plurality of heat exchanger units 1 similar to that previously describea in Figs. 1 and 2. The heat exchanger units 1 are supported in two rows so that the passages within such heat exch~ngers extend substantially vertically. As shown in Fig. 5, cool ambi~nt air flows upward in ~ !j 20 the direction of arrows 4 through one set of passages and hot exhaust air flows downward in the direction of arrows 7 thr~iugh the other set of passages. The two sets of passages are separated from each other by the ' ' ! . `
heat exhanger plates a~ shown in Fig. 2.
In the preferred em~odiment, the heat exchanger apparatus of Figs. 4 and 5 is employed to cool and ~b~ condense pollutants from hot contaminated exhaust aix such as i9 emitted ~y a wood veneer dryer. The cold .,,~
~;1 ambient air cools the hot exhaust air as it passes : ~
~ 30 downward through the heat exchanger and causes ~ carbonaceous vapors and other gaseous pollutants :~ -14-JC pw l~t~3--19~0 ~r,~76 ~1 contained within the exhaust air to condense onto the surfaces of the heat exchanger passageways. The condensed pollutants are deposited as liquidc onto the surfaces of the heat exchanger plates so that they drain down such heat exchanger plates by gravity into an exhaust air collection duct 66 extending horizontally along the bottoms of the heat exchanger units. The exhaust air is sucked from the bottom end of the heat exchangers in the direction of arrows 67 through duct 66 by an exhaust a~r fan 68 to an exhaust discharge 70 which may be connected to a suitable exhaust stack (not shown) which opens to the atmosphere. As a result of the suction of the exhaust fan, a slightly negative pressure is produced in duct 66 and the exhaust air passages of the heat exchanger units 1 and the exhaust air input ducting to such exchanger. ~he bottom of the exhaust duct 66 slopes downwardly to a collec-tion tank 72 where the liquid pollutants;are collected . i - .. , -. for periodic removal.
~he contaminated exhaust air is transmitted into thP apparatus of Fig. 4 through an exhaust inlet duct 74. A filter sect~on 76 is provided in the inlet i~ duct to filter solid particles from the exhaust air before it is transmitted to a pair of side ducts 78 . .
, q`~ and 80 extending horizontally across the top ends of -the two rows of heat exchanger units. The exhaust air is transmitted through side ducts 78 and 80 in the , ~ :
direation of arrows 81 and downward through the heat exchanger unit~.
.-~ 30 Cold, clean ambient air is transmitted from :: ,~; - ~ - . .
~ the atmo~phere upward through inlet openings 82 in the , .

~, :
' ~. :

JC:pw 19~33~ 3n ?~ 7~

bottom ends of the heat exchanger units 1 anc~. the heated clean air îs discharged into a central duct 84 through outlet openings 86 at the top ends of such heat exchanger units, as shown in Fig. 5. ~he central duct 84 extends horizontally between the two side ducts 78 and 80 acro~s the top ends of the heat exchanger units and connect~ to a vert.ical duct 88.
The heated clean air is sucked through ducts 84 and 88 in the direction of arrows 89 by another air fan 90 connected between the bottom of duct 88 and clean air discharge 92, which may be connected by suitable ducting (not shown) back to the veneer dryer or to the heating system of a building. ~his re~ults in a considerable savings in heating costs since approx-imately 70% of the heat in the exhaust air is recovered by heat transfer in the heat exchangers to the clean air.
In order to control the temperature of the exhaust air emitted from the output of the heat exchanger units 1, a temperature sensor 94 is located at the output of the exhaust air collector auct 6~
and is electrically connected to a solenoid ~6 or :
other actuating means which controls the opening and closing of a damper mechanism 98 provided in the path -of the clean air, such as in the vertical duct 88. P~s a result, the flow of clean air through the vertical duct and the heat exchangers is automatically changed to vary the amount of cooling of the exhaust air in order to maintain the final temperature of the exhaust air at the output of the heat exchangers at a predetermined temperature of, for example, 150F.

,. ~ . . , ' '' ': " .
. . .

J(`:L!~i 19~!S3-19d~n 2~7hj7~

This is necessary, among other reasons, to maintain the condensed pollutants in a liquid state so they run down the surfaces of the heat exchanger passages and duct 66 into the collection tank 72.
Typical temperatures of the exhaust air and clean air before and after heat exchange are as follows~ The exhaust air temperature is about 340F.
at inlet 74 and 150F. at the outlet of duct 66. The clean air temperature is at an ambient level of, for example, 70F. at inputs 82 and about 26nF. at discharge 92 because of the heat exchange increase in temperature of about 190F.
As a result of the drop in temperature of the exhaust air from 340F. to 150F., substantial].y all carbonaceous vapors and other gaseous pollutants in the exhaust air are condensed onto the heat exchanger passageways and very little pollutants are ; transmitted into the atmosphere through the exhaust dischaxge 70 so that in many cases no further pollution abatement equipment is necessary. Howaver, a demister apparatus 100 is employed connected between the output of the exhaust air collection duct 66 and the exhaust fan 68. The demister apparatus is of conventional type which contains a plurality of baffle~
for changing the direction of the air flow in order to : -remove any partlcles of liquid or mist of condensed water or pollutants from the exhaust air which are not deposited on the surfaces of the heat exchanger or ?, ~
duct 66. The demister also drains into the aollection tank 72.

The heat exchan~er passages through which the , ., ~rc pw 1~3-]9~9~ 2/~

exhaust air is conducted downward in the direction of arrow 7 may be cleaned by spraying clean liquîd into such passageways through the pipe line 54 into the sprayers 51, in a similar manner to that shown in Figs. 1 and 2. ~hus, in~tead of spraying water for condensing purposes as in Fig. 1, the sprayer apparatus 6 can be employed to spray cleaning liquid or steam for removing condensation solids and other deposits from the surface of the exhaust air passages.
It will be obvious to those having ordinary skill in the art that many changes may be made in the details of the above-described pxeferred embodiment of the present invention without departing from the spirit of the invention. For example, the exhaust gas can flow upward in direction 4 while ambient air or cold water flows downward in direction 7 in Fig. 5, ~; merely by moving side ducts 78 and 80 to the lower ends of the heat exbhangers and providing the fluid inlets 82 at the top ends of such exchangers. In this case the duct 84 would discharge the exhaust air and liquid drain means like 60 and 61 of Fig. 1 would be provided in the lowered side ducts 78 and 80 to remove the conden~ed pollutants, while duct 66 would be used to discharge the heated ambient air or water.
, Therefore, the scope of the present invention should only be determined by the following claims.

.

. .

Claims (24)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heat exchanger apparatus comprising counterflow heat exchanger means including a first set and a second set of heat exchanger passages separated from each other by heat exchanger plates in heat exchanging relationship with said first and second passages on opposite sides thereof, both sets of said passages extending completely through the heat exchanger between inlets and outlets;
support means for supporting the heat exchanger means so that said passages extend substantially vertically between their top ends and bottom ends;
gas transmission means for transmitting gas into inlets at the bottom ends of the first passages and causing said gas to flow upward through said first passages out of outlets at their top ends; and liquid transmission means for spraying liquid directly onto the surfaces of the heat exchanger plates in the second passages adjacent the top ends thereof and causing said liquid to flow downward through said second passages along said surfaces and out of outlets at their bottom ends so that said liquid and said gas flow in opposite directions along the surfaces on opposite sides of the same portion of one of said heat exchanger plates fox direct counterflow heat exchange laterally through the thickness of said plates.

2. A heat exchanger apparatus in accordance with claim 1 in which the liquid transmission means includes liquid sprayer means extending within the heat exchanger for spraying a thin film of liquid onto the surfaces of the second passages.

3. A heat exchanger apparatus in accordance with claim 2 in which the sprayer means includes a plurality of perforated sprayer tubes extending across the top ends of the second passages.

4. A heat exchanger apparatus in accordance with claim 1 in which the gas transmission means transmits heated air into the first passages and the liquid transmission means transmits cold water into the second passages.

5. A heat exchanger apparatus in accordance with claim 4 in which the heated air is of high humidity so that at least a portion of the moisture in said air condenses on the surfaces of the first passages and the condensed water is removed from the heat exchanger by a drain means connected to the bottom end of the first passages.

6. A heat exchanger apparatus in accordance with claim 2 in which the liquid transmission means includes water sprayer means mounted outside the heat exchanger passages above the upper ends of the second passages.

7. A heat exchanger apparatus in accordance with claim 4 in which the heated air contains pollutants that are cooled sufficiently to condense on the surfaces of the first passages, and which includes means for removing the condensed pollutants from the heat exchanger.

8. A heat exchanger apparatus comprising:
counterflow heat exchanger means including a first set and a second set of heat exchanger passages separated from each other by heat exchanger plates in heat exchanging relationship with said first and second passages, both of said sets of passages extending completely through said heat exchanger between inlets and outlets, said heat exchanger plates having their ends split into two end portions which are joined to different heat exchanger plates on opposite sides thereof to form said first and second passages;
support means for supporting the heat exchanger apparatus so that said passages extend substantially vertically between top ends and bottom ends;
first transmission means for transmitting a gas into inlets at the bottom ends of the first passages and causing said gas to flow upward through said first passages out of outlets at their top ends; and second transmission means for transmitting another fluid into inlets at the top ends of the second passages and cause said other fluid to flow downward through said second passages along said surfaces and out of outlets at their bottom ends.

9. A heat exchanger apparatus in accordance with claim 8 in which the gas is air and the other fluid is liquid.

10. A heat exchanger apparatus in accordance with claim 9 in which the second transmission means is a water sprayer means including a plurality of perforated sprayer tubes mounted within the heat exchanger and extending across the top ends of the second passages,

11. A heat exchanger apparatus in accordance with claim 9 in which the first transmission means transmits heated air into the first passages and the second transmis-sion means transmits cold water into the second Passages.

12. A heat exchanger apparatus in accordance with claim 11 in which the heated air is of high humidity so that at least a portion of the moisture in said air condenses on the surface of the first passages and the condensed water is removed from the heat exchanger by a drain means connected to the bottom end of the first passages.

13. A heat exchanger apparatus in accordance with claim 11 in which the heated air contains gaseous pollutants that are cooled sufficiently by the cold water to condense on the surfaces of the first passages as liquid pollutants which flow down said first passages and out of the heat exchanger.

14. A heat exchanger apparatus in accordance with claim 8 in which the first and second fluids are air streams of different temperatures, one of such air streams being heated exhaust air containing gaseous pollutants which are cooled sufficiently by the colder air stream to condense on the surfaces of one set of passages in the heat exchanger as liquid pollutants which flow down said one set of passages and out of the heat exchanger.

15. A heat exchanger apparatus in accordance with claim 14 which also includes cleaning means for transmitting cleaning fluid into the one set of passages for removing any solid material which is deposited on the surfaces of said one passages.

16. A heat exchanger and condenser apparatus comprising: a plurality of counterflow heat exchanger units each including a first set and a second set of passages separated from each other by heat exchanger plates in heat exchanging relationship with the first and second passages on opposite sides thereof; support means for supporting the heat exchanger units in at least two rows so that said passages extend sub-stantially vertically between their top and bottom ends; a pair of inlet conduits each extending across one of the ends of each of the heat exchanger units in a different row; an intermediate conduit extending between said pair of conduits across said one end of both rows of heat exchanger units; a discharge conduit extending across the other ends of both rows of heat exchanger units; first transmission means for trans-mitting hot exhaust air in through said pair of conduits, through said first set of passages in said heat exchanger units and out through said discharge conduit;
and second transmission means for transmitting another fluid through said second passages in said heat exchanger units in the opposite direction to said exhaust air and out through said intermediate conduit, said other fluid being colder than the exhaust air to cool said exhaust air sufficiently to cause gaseous pollutants therein to condense on the surfaces of said first passages as liquid pollutants which flow down said first passages and out of the heat exchanger units.

17. Apparatus in accordance with claim 16 in which the liquid pollutants flow down the discharge conduit into a collecting tank.

18. Apparatus in accordance with claim 16 in which said other fluid is ambient air, the first transmission means includes an exhaust fan connected to the output of the discharge conduit which produces a negative pressure below that of the surrounding atmosphere, within the discharge conduit, the first passages of the heat exchanger units, and the pair of inlet conduits.

19. Apparatus in accordance with claim 16 which includes a temperature sensor means for detecting the output temperature of the exhaust air in the discharge conduit and for producing a corresponding electrical control signal, the other fluid is ambient air, and also includes control means for adjusting the flow of ambient air through said heat exchanger in response to said control signal for maintaining said output temperature within a perdetermined range of temperatures.

20. Apparatus in accordance with claim 19 in which the control means includes a damper means for changing the amount of air flowing through said intermediate conduit.

21. Apparatus in accordance with claim 16 which also includes a demister means connected to the output of the discharge conduit for removing liquid mist from the exhaust air.

22. Apparatus in accordance with claim 16 in which the heat exchanger plates in the heat exchanger units have their ends split into two end portions which are joined to different heat exchanger plates on opposite sides thereof to form said first and second passages.

23. A heat exchanger apparatus in accordance with claim 8 in which the first fluid is hot air and which also includes cleaning means for evaporating cleaning liquid into said hot air and for condensing said cleaning liquid on the surfaces of the first set of passages to cause said cleaning liquid to flow down said first passages to remove solids deposited on the surfaces of said first passages.

24. A heat exchanger apparatus in accordance with claim 23 in which the condensed cleaning liquid is collected and reevaporated into the hot air to provide continuous cleaning.